The subject matter disclosed herein relates generally to imaging systems, and more particularly to methods and systems for axially segmenting Positron Emission Tomography (PET) data.
PET systems generate images that represent the distribution of positron-emitting nuclides within the body of a subject 16. When a positron interacts with an electron by annihilation, the entire mass of the positron-electron pair is converted into two 511 keV photons. The photons are emitted in opposite directions along a line of response. The annihilation photons are detected by detectors that are placed along the line of response on a detector ring. When these photons arrive and are detected at the detector elements at the same time, this is referred to as coincidence. An image is then generated based on the acquired emission data includes the annihilation photon detection information.
In operation, at least some known PET systems acquire the emission data using a step-and-shoot method. For example, the subject 16 is positioned at a first axial position within the PET imaging system. Emission data is then acquired at the first axial position. Subsequently, the subject 16 is then moved to a second axial position wherein additional emission data is acquired. Thus, the subject 16 is moved to a plurality of axial positions within the PET imaging system to acquire the emission data.
However, in some instances the sensitivity of the PET detector is not uniform over the entire scan. Thus, the emission data acquired using the step-and-shoot mode of operation may have a non-uniform signal-to-noise ratio (SNR). More specifically, the sensitivity profile may be uneven such that some of the images reconstructed using emission data acquired during the step-and-shoot mode of operation may have inconsistent quality. Moreover, because the emission data is acquired at different individual axial positions, a weighted average must be utilized to perform reconstruction at the area where the images overlap, such that the reconstruction of various frames forming the image is performed one frame at a time.